Description

Version 4 is designed for short shaft PG35L-048 motors (8mm). This version has integrated bearing to appose idler tension. Use of the external bearing is no longer needed. Also, this body has a snap-in slot for a J-Head hot end which eliminates the aluminum slot plate. The snap-in idea was derived from scottmayson. This Micro Extruder has been tested on MendelMax and Prusa.

Go to www.ultibots.com for Hobbed Drive Gears and Bearings. MendelMax 1.5+ kits and printed parts are available for purchase.

I would recommend pulling the motor from the body, turn down the pot counter clockwise, then make incremental micro turns clockwise, pinch the hobbed drive gear, then run the stepper 10mm at 100mm/sec in Pronterface. Keep making the micro adjustments until holding the drive gear becomes difficult. I have found too much amperage to the stepper is problematic.

Regarding motor shaft wobble, our production printers have been running almost daily for months without issue. Our retract is set to 15mm/sec and we are using RAMPS 1.4 with A4988 stepper motor driver using 24 volts input.

This extruder works well with AlephObjects Supa-Flat X-Carriage
thingiverse.com/thing:10646
The bearing holders shown are:
thingiverse.com/thing:15205, the last one on the download list.
SDP_bearing_mount_for_y_axis__on_side_with_square_ends_and_fixed_holes_by_Simon.stl file.

I would recommend pulling the motor from the body, turn down the pot counter clockwise, then make incremental micro turns clockwise, pinch the hobbed drive gear, then run the stepper 10mm at 100mm/sec in Pronterface. Keep making the micro adjustments until holding the drive gear becomes difficult. I have found too much amperage to the stepper is problematic.

Regarding motor shaft wobble, our production printers have been running almost daily for months without issue. Our retract is set to 15mm/sec and we are using RAMPS 1.4 with A4988 stepper motor driver using 24 volts input.

Brad, I've given up on trying to fit the extruder above the print platform on the standard Rostock, just not enough room. I tried modifying your PRT file, but my skill at Alibre PE is quite lacking. Anyway, what I'd like to do is modify this design to mount below the platform. What would have to be done is to trim out the bottom so that it looks like the top, with curved ends to minimize weight and interferences. The top, which would attach to the print platform, would be squared off to attach to the 4mm bolt holes on the platform. These would be 43mm apart, centered on the filament feed hole, with inserts for mounting 4mm nuts.

If you want to pursue this, I think you might have another product which you could offer.

Already printed one, and promptly started hacking away at it to fit within the confines of my Delta Rostock print platform. Looks like the motor hitting the delta arms will constrain the motion of the printer somewhat, but still will be something like 220mm by 180mm build area.

Thanks for the design, really like the built in supports for printing. Got a little sloppy for the idler bearing support, but it will be fine with the washers and 4mm bolt in there.

Do you suppose I'll need to do something to the feed holes to use 1.75mm filament with this?

Getting those gears off is certainly quite the adventure. I bought 20 of the PG35L's with the gear attached. I tried all kinds of printed solutions, various Dremel cutting wheels and just plain cursing at the damn things. In the end I wound up using this tool and lube to get them off.

The lube goes on the threads for the faucet puller and makes a huge difference in getting the gears off! I also put a drop on the tip of the PG35L shaft as well to help protect the tool and motor from excess friction.

Thank you so much for the modified short shaft design. I thought I was going to wind up using these motors as paper weights forever!